Proposal to Defer Emissions from Bioenergy and Other Biogenic Sources

It will hardly come as news that since January 2, 2011, stationary sources planning to either perform major modifications or build new facilities have been required to consider greenhouse gas (GHG) emissions during the process of obtaining their pre-construction permits. However, a number of sources currently affected by these requirements may be afforded temporary relief, as U.S. EPA has proposed to defer the consideration of carbon dioxide (CO2) emissions from bioenergy and other biogenic sources (i.e., biogenic CO2 emissions) when determining whether a stationary source meets the Prevention of Significant Deterioration (PSD) and Title V applicability thresholds, including those for the application of Best Available Control Technology (BACT). The proposed deferral period is three (3) years. The proposed rule does not impact other Federal programs which require consideration of GHGs, such as the New Source Performance Standards or Mandatory Reporting Rule programs.

The term “biogenic CO2 emissions” is defined in the March 21, 2011 proposed rule as emissions of CO2 from a stationary source directly resulting from the combustion or decomposition of biologically-based materials other than fossil fuels. The proposed deferral applies only to biogenic CO2 emissions and does not affect non-GHG pollutants or other GHGs (e.g., methane (CH4) and nitrous oxide (N2O)) emitted from the combustion of biomass fuel. The proposed deferral clarifies that biogenic CO2 emissions from stationary sources which co-fire fossil fuel and biologically-based fuel, and/or combust mixed fuels (e.g., tire-derived fuels, municipal solid waste (MSW), etc.), are included under the proposed deferral. However, the fossil fuel-derived CO2 emissions are not. U.S. EPA has specifically requested comment on whether this deferral should specify that stationary sources subject to the PSD and Title V programs use a specific method(s) for determining their biogenic portion of CO2 emissions. U.S. EPA is also seeking comment on other ways to ensure that there is an accurate estimate of how much biogenic CO2 is subject to the deferral for a specific facility, particularly when combusting mixed fuels. Comments will be accepted through May 5, 2011.